3(j THE HIND LEGS. 



Considering the sit nation and action of this joint, the weight and stress thrown 



upon it .nust be exceedingly great 



CUT OF THE HOCK. and it is necessarily liable to much 



injury in rapid and powerful mo- 

 tion. What are the provisions U 

 prevent injury ? The grooved of 

 pulley-like heads of the tibia and 

 the astragalus, received deeply 

 into one another, and confined by 

 powerful ligaments, admitting 

 a freely of hinge-like action ; but 

 of no side motion, to which the 

 joint would otherwise be exposed 

 in rapid movement, or on an un- 

 even surface. A slight inspection 

 of the cut will show that the stress 

 or w r eight thrown by the tibia a 

 on the astragalus 6, does not 

 descend perpendicularly, but in a 

 slanting direction. By this much 

 concussion is avoided, or more 

 readily diffused among the dif- 

 ferent bones ; and, the joint con- 

 sisting of six bones, each of them 

 covered with elastic cartilage, and 

 each admitting of a certain degree 

 of motion, the diminished con- 

 cussion is diffused among their, 

 all, and thereby neutralised and 

 rendered comparatively harmless. 

 Each of these bones is covered 

 not only by cartilage, but by a 

 membrane secreting synovia; so 

 that, in fact, these bones are 

 formed into so many distinct 

 joints, separated from each other, 

 and thereby guarded from injury, 

 yet united by various ligaments 

 possessing altogether sufficient 

 motion, yet bound together so 

 strongl)' as to defy dislocation. 

 When, however, the work which 

 this joint has to perform, and the 

 thoughtlessness and cruelty with 

 which that work is often exacted, 

 are considered, it will not excite 

 any surprise if this necessarily complicated mechanism is sometimes deranged. The 

 hock, from its complicated structure and its work, is the principal seat of lameness 

 behind. 



ENLARGEMENT OF THE HOCK. 



First, there is inflammation, or sprain of the hock-joint generally, arising from sud- 

 den violent concussion, by some check at speed, or over-weight, and attended with 

 enlargement of the whole joint, and great tenderness and lameness. This, however, 

 like other diffused inflammations, is not so untractable as an intense one of a more 

 circumscribed nature, and by rest and fomentation, or, perchance, firing, the limb 

 recovers its action, and the horse becomes fit for ordinary work. 



The swelling, however, does not always subside. Enlargement, spread over the 

 wtaolo of the hock-joint, remains. A horse with in enlarged hock must always be 

 regarded with suspir ion. In truth, he is unsound. The parts, altered in structure, 

 jwst be to a certain iegree weakened, "^he animal may discharge his usual worl 



